MG ZS EV: Leaving at 100 SOC

[Kraiklyn]

Is it ok to leave the new facelift MG ZS EV 2022 at 100 SOC for a few days? I have a leaf where it's advised not to do this for long to avoid battery degradation.

I know the MG has a different battery chemistry.

 

[TassieDi]

Yes. This is one of the reasons I got this model. The LFP battery chemistry is claimed to be fine with repeated charging to 100pc.

 

[Kraiklyn]

Yes. This is one of the reasons I got this model. The LFP battery chemistry is claimed to be fine with repeated charging to 100pc.

Thanks. What about charging it to 100% and leaving it sitting for a few days? Would that do any harm?

 

[Gadget Geek]

Is it ok to leave the new facelift MG ZS EV 2022 at 100 SOC for a few days? I have a leaf where it's advised not to do this for long to avoid battery degradation.

I know the MG has a different battery chemistry.

SR or LR?
SR = yes
LR = no.

 

[Kithmo]

Personally, I wouldn't be happy leaving either chemistry standing at 100%.
Having said that, the BMS won't let you charge to 100% anyway.
When the car says it's at 100% it's probably somewhere between 95-97% (guess)

 

[RobinH]

If it's a one off and it's only a few days I wouldn't worry about it at all.

 

[Kraiklyn]

Thanks all, it's just a new SR version. The LR's haven't made it to NZ yet. It's not something I would do regularly just occasionally charge up off the solar when the opportunity arises and then may not have anywhere to go for 24 hours.

I guess I can always run the heaters for a while to drop it back a bit if needed.

 

[N2STY]

I guess I can always run the heater for a while if I need to drop it back down a bit.

I am sure you will be fine but if you have free spare energy you would be mad not to buy a V2L adapter put that to good use

 

[Hairyfool]

The issue is really about for leaving it weeks rather than days. So as long as it is for "few days" then that shouldn't be a problem.

Of course you have to be confident about what you are doing to leave it, is there any possibility it could extend beyond what you expect.

 

[RobinH]

Is there a storage mode on the ZS? Some other EV's have a switch to disconnect everything if you are leaving it for more than a couple of days.

 

[Gadget Geek]

Is there a storage mode on the ZS? Some other EV's have a switch to disconnect everything if you are leaving it for more than a couple of days.

Yes. It's called a 10mm spanner.

 

[RobinH]

Yes. It's called a 10mm spanner.

Ah, same as the Volt then!

 

[JCFlippen]

Is there a storage mode on the ZS? Some other EV's have a switch to disconnect everything if you are leaving it for more than a couple of days.

Yes probably 80%.

 

[thingaby]

Yes. This is one of the reasons I got this model. The LFP battery chemistry is claimed to be fine with repeated charging to 100pc.

I watched a youtube on the cleanerwatt channel a couple of days ago. It basically said that any battery charged to 100% is put under strain. However, the LFP batteries have to be charged to !00% to effectively reset the remaining range calculation because the LFP chemistry range calculation is based on voltage drop unlike NCM chemistry. If you watch the youtube do read the comments because there are some very erudite comments about why that is. I think we need Coulomb to comment on this.

 

[Coulomb]

I think we need Coulomb to comment on this.

Most if it has been said pretty well.

I've softened my stance a little on charging LFP to 100%. Degradation is all about cell voltage and temperature; both encourage reactions, good and bad. So hot battery cells perform better, but degrade faster. But the damage depends on the time at the high temperature and voltage. That's why Teslas will preheat a battery to get the highest fast charge rate; because it's short duration, it won't harm the battery significantly.

Temperature is usually hard to avoid, though if you can park your car in the shade in summer, it's worth doing that.

LFP cell voltage is already about 15% lower than that of NMC, going by either nominal voltage (3.2 versus 3.75 V, or fully charged voltage (3.6 versus 4.2 V). That's why overall, LFP lasts longer. It lasts more than 15% longer because it's a sort of exponential effect.

LFP has one more trick: once you fully charge the cell to 3.6 V (sometimes 3.65 V), the voltage relaxes to about 3.5 V over an hour or so, so that's another 3% advantage in resting voltage. This relaxation of terminal voltage doesn't seem to cause significant reduction in stored energy. If you use the car right away after charging, the extra voltage disappears very soon anyway, so charging to the highest voltage doesn't store much extra energy. So if you're really paranoid about battery life, you could try to charge to say 98% max. Sadly, MG doesn't help you with this, as they disable the charge SoC limit on the SR models. I don't know if charging to 98% is enough to reset the BMS SoC guesstimate; it should be, because by then the cell should be on one of the steep parts of the voltage versus SoC curve.